Radio frequency front end module including supplemental filter

ABSTRACT

Radio frequency front end modules are provided. In one aspect, a front end system includes at least one power amplifier configured to amplify a transmit radio frequency signal, at least one low noise amplifier configured to receive a receive radio frequency signal, an output node coupled to an antenna. The front end system also includes a first switch configured to selectively couple the output node to the at least one power amplifier during a transmit period and to the at least one low noise amplifier during a receive period, at least one transmit filter coupled between the power amplifier and the at least one switch, and at least one receive filter coupled between the low noise amplifier and the at least one switch. The front end system further includes a transmit supplemental filter, a receive supplemental filter, and a second switch.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Technological Field

Aspects of this disclosure relate to radio frequency (RF) communicationsystems, and in particular, front end modules for use in RFcommunication systems.

Description of the Related Technology

RF communication systems include a front end which couples one or moreantennas to transmit and receive paths that communicate the RF signalsto/from a baseband system. During time-division duplexing (TDD)communication, the antennas may be connected to only one of the transmitand receive paths at a time. The front end further includes one or morefilters configured to filter out frequencies from the RF signals thatare not within a given communication band. Typically, the filters may beshared between the transmit and receive paths.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

In one aspect, there is provided a radio frequency front end systemcomprising: at least one power amplifier configured to amplify atransmit radio frequency signal and at least one low noise amplifierconfigured to receive a receive radio frequency signal; a first switchconfigured to selectively couple an output node coupled to an antenna tothe at least one power amplifier during a transmit period and to the atleast one low noise amplifier during a receive period; at least onetransmit filter coupled between the power amplifier and the at least oneswitch and at least one receive filter coupled between the low noiseamplifier and the at least one switch, a transmit supplemental filterand a receive supplemental filter; and a second switch configured toselectively couple the transmit supplemental filter to the at least onepower amplifier during the transmit period and to couple the receivesupplemental filter to the at least one low noise amplifier during thereceive period.

The first switch and the second switch can be ganged together.

The front end system can further comprise a common filter coupledbetween the first switch and the output node.

The at least one power amplifier can include a plurality of poweramplifiers, and the at least one low noise amplifier can include aplurality of low noise amplifiers.

The transmit and receive supplemental filters can include shunt filters.

The shunt filters can be configured to reject predetermined portions ofan RF spectrum.

The transmit and receive supplemental filters can include notch filters.

The transmit and receive supplemental filters can be entirely differentfrom the at least one transmit filter and the at least one receivefilter in center frequency and frequency response.

The second switch can be further configured to dynamically reconfigurethe least one transmit filter and the at least one receive filter byswitching in one of the first and second supplemental filters into asignal path between at least one power amplifier, the at least one lownoise amplifier; and the output node.

In another aspect, there is provided a mobile device comprising: anantenna configured to transmit radio frequency signals to a basestation; and a front end system coupled to the antenna and configured totransmit and receive the radio frequency signals from the antenna, thefront end system including a at least one power amplifier configured toamplify a transmit radio frequency signal, at least one low noiseamplifier configured to receive a receive radio frequency signal, afirst switch configured to selectively couple the antenna to the atleast one power amplifier during a transmit period and to the at leastone low noise amplifier during a receive period, at least one transmitfilter coupled between the power amplifier and the at least one switch,at least one receive filter coupled between the low noise amplifier andthe at least one switch, a transmit supplemental filter, a receivesupplemental filter, and a second switch configured to selectivelycouple the transmit supplemental filter to the at least one poweramplifier during the transmit period and to couple the receivesupplemental filter to the at least one low noise amplifier during thereceive period.

The first switch and the second switch can be ganged together.

The front end system can further include a common filter coupled betweenthe first switch and the output node.

The at least one power amplifier can include a plurality of poweramplifiers, and the at least one low noise amplifier can include aplurality of low noise amplifiers.

The transmit and receive supplemental filters can include shunt filters.

The shunt filters can be configured to reject predetermined portions ofan RF spectrum.

The transmit and receive supplemental filters can include notch filters.

The transmit and receive supplemental filters can be entirely differentfrom the at least one transmit filter and the at least one receivefilter in center frequency and frequency response.

In yet another aspect, there is provided a method of operating a radiofrequency front end system, the method comprising: coupling, via a firstswitch, at least one power amplifier to an antenna during a transmitperiod, the first switch coupled to the at least one power amplifier viaat least one transmit filter; coupling, via the first switch, at leastone low noise amplifier to the antenna during a receive period, thefirst switch coupled to the at least one low noise amplifier via atleast one receive filter; coupling, via a second switch, a transmitsupplemental filter to the at least one power amplifier during thetransmit period; and coupling, via the second switch, a receivesupplemental filter to the at least one low noise amplifier during thereceive period.

A common filter can be coupled between the at first switch and theantenna.

The at least one power amplifier can include a plurality of poweramplifiers, and the at least one low noise amplifier can include aplurality of low noise amplifiers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of one example of a communicationnetwork.

FIG. 1B is a schematic diagram of one example of a mobile devicecommunicating via cellular and WiFi networks.

FIG. 2 is a schematic diagram of one embodiment of a mobile device.

FIG. 3 is a schematic diagram of a power amplifier system according toone embodiment.

FIG. 4A is a schematic diagram of one embodiment of a packaged module.

FIG. 4B is a schematic diagram of a cross-section of the packaged moduleof FIG. 4A taken along the lines 4B-4B.

FIG. 5 is a schematic diagram of one embodiment of a transceiver/RFfront end.

FIG. 6A is an example multiband RF front end which can be used for TDDin accordance with aspects of this disclosure.

FIG. 6B is another example multiband RF front end which can be used forTDD in accordance with aspects of this disclosure.

FIG. 6C is yet another example multiband RF front end which can be usedfor TDD in accordance with aspects of this disclosure.

FIG. 7A illustrates an example portion of an RF front end for two bandsin accordance with aspects of this disclosure.

FIG. 7B illustrates another example portion of an RF front end for twobands in accordance with aspects of this disclosure.

FIG. 7C illustrates yet another example portion of an RF front end fortwo bands in accordance with aspects of this disclosure.

FIG. 7D illustrates still yet another example portion of an RF front endfor two bands in accordance with aspects of this disclosure.

FIG. 8 illustrates an example portion of an RF front end for three bandsin accordance with aspects of this disclosure.

FIG. 9A illustrates an example portion of an RF front end for a singleband in accordance with aspects of this disclosure.

FIG. 9B illustrates another example portion of an RF front end for asingle band in which separate filters are provided for the transmit andreceive paths in accordance with aspects of this disclosure.

FIG. 9C illustrates an example portion of an RF front end for a singleband in accordance with aspects of this disclosure.

FIG. 10A illustrates an example portion of an RF front end for a singleband in accordance with aspects of this disclosure.

FIG. 10B illustrates another example portion of an RF front end for asingle band in accordance with aspects of this disclosure.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The following detailed description of certain embodiments presentsvarious descriptions of specific embodiments. However, the innovationsdescribed herein can be embodied in a multitude of different ways, forexample, as defined and covered by the claims. In this description,reference is made to the drawings where like reference numerals canindicate identical or functionally similar elements. It will beunderstood that elements illustrated in the figures are not necessarilydrawn to scale. Moreover, it will be understood that certain embodimentscan include more elements than illustrated in a drawing and/or a subsetof the elements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

The International Telecommunication Union (ITU) is a specialized agencyof the United Nations (UN) responsible for global issues concerninginformation and communication technologies, including the shared globaluse of radio spectrum.

The 3rd Generation Partnership Project (3GPP) is a collaboration betweengroups of telecommunications standard bodies across the world, such asthe Association of Radio Industries and Businesses (ARIB), theTelecommunications Technology Committee (TTC), the China CommunicationsStandards Association (CCSA), the Alliance for TelecommunicationsIndustry Solutions (ATIS), the Telecommunications Technology Association(TTA), the European Telecommunications Standards Institute (ETSI), andthe Telecommunications Standards Development Society, India (TSDSI).

Working within the scope of the ITU, 3GPP develops and maintainstechnical specifications for a variety of mobile communicationtechnologies, including, for example, second generation (2G) technology(for instance, Global System for Mobile Communications (GSM) andEnhanced Data Rates for GSM Evolution (EDGE)), third generation (3G)technology (for instance, Universal Mobile Telecommunications System(UMTS) and High Speed Packet Access (HSPA)), and fourth generation (4G)technology (for instance, Long Term Evolution (LTE) and LTE-Advanced).

The technical specifications controlled by 3GPP can be expanded andrevised by specification releases, which can span multiple years andspecify a breadth of new features and evolutions.

In one example, 3GPP introduced carrier aggregation (CA) for LTE inRelease 10. Although initially introduced with two downlink carriers,3GPP expanded carrier aggregation in Release 14 to include up to fivedownlink carriers and up to three uplink carriers. Other examples of newfeatures and evolutions provided by 3GPP releases include, but are notlimited to, License Assisted Access (LAA), enhanced LAA (eLAA),Narrowband Internet of things (NB-IOT), Vehicle-to-Everything (V2X), andHigh Power User Equipment (HPUE).

3GPP introduced Phase 1 of fifth generation (5G) technology in Release15, and plans to introduce Phase 2 of 5G technology in Release 16(targeted for 2020). Subsequent 3GPP releases will further evolve andexpand 5G technology. 5G technology is also referred to herein as 5G NewRadio (NR).

5G NR supports or plans to support a variety of features, such ascommunications over millimeter wave spectrum, beamforming capability,high spectral efficiency waveforms, low latency communications, multipleradio numerology, and/or non-orthogonal multiple access (NOMA). Althoughsuch RF functionalities offer flexibility to networks and enhance userdata rates, supporting such features can pose a number of technicalchallenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR.

FIG. 1A is a schematic diagram of one example of a communication network10. The communication network 10 includes a macro cell base station 1, asmall cell base station 3, and various examples of user equipment (UE),including a first mobile device 2 a, a wireless-connected car 2 b, alaptop 2 c, a stationary wireless device 2 d, a wireless-connected train2 e, a second mobile device 2 f, and a third mobile device 2 g.

Although specific examples of base stations and user equipment areillustrated in FIG. 1A, a communication network can include basestations and user equipment of a wide variety of types and/or numbers.

For instance, in the example shown, the communication network 10includes the macro cell base station 1 and the small cell base station3. The small cell base station 3 can operate with relatively lowerpower, shorter range, and/or with fewer concurrent users relative to themacro cell base station 1. The small cell base station 3 can also bereferred to as a femtocell, a picocell, or a microcell. Although thecommunication network 10 is illustrated as including two base stations,the communication network 10 can be implemented to include more or fewerbase stations and/or base stations of other types.

Although various examples of user equipment are shown, the teachingsherein are applicable to a wide variety of user equipment, including,but not limited to, mobile phones, tablets, laptops, IoT devices,wearable electronics, customer premises equipment (CPE),wireless-connected vehicles, wireless relays, and/or a wide variety ofother communication devices. Furthermore, user equipment includes notonly currently available communication devices that operate in acellular network, but also subsequently developed communication devicesthat will be readily implementable with the inventive systems,processes, methods, and devices as described and claimed herein.

The illustrated communication network 10 of FIG. 1A supportscommunications using a variety of cellular technologies, including, forexample, 4G LTE and 5G NR. In certain implementations, the communicationnetwork 10 is further adapted to provide a wireless local area network(WLAN), such as WiFi. Although various examples of communicationtechnologies have been provided, the communication network 10 can beadapted to support a wide variety of communication technologies.

Various communication links of the communication network 10 have beendepicted in FIG. 1A. The communication links can be duplexed in a widevariety of ways, including, for example, using frequency-divisionduplexing (FDD) and/or time-division duplexing (TDD). FDD is a type ofradio frequency communications that uses different frequencies fortransmitting and receiving signals. FDD can provide a number ofadvantages, such as high data rates and low latency. In contrast, TDD isa type of radio frequency communications that uses about the samefrequency for transmitting and receiving signals, and in which transmitand receive communications are switched in time. TDD can provide anumber of advantages, such as efficient use of spectrum and variableallocation of throughput between transmit and receive directions.

In certain implementations, user equipment can communicate with a basestation using one or more of 4G LTE, 5G NR, and WiFi technologies. Incertain implementations, enhanced license assisted access (eLAA) is usedto aggregate one or more licensed frequency carriers (for instance,licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensedcarriers (for instance, unlicensed WiFi frequencies).

As shown in FIG. 1A, the communication links include not onlycommunication links between UE and base stations, but also UE to UEcommunications and base station to base station communications. Forexample, the communication network 10 can be implemented to supportself-fronthaul and/or self-backhaul (for instance, as between mobiledevice 2 g and mobile device 2 f).

The communication links can operate over a wide variety of frequencies.In certain implementations, communications are supported using 5G NRtechnology over one or more frequency bands that are less than 6Gigahertz (GHz) and/or over one or more frequency bands that are greaterthan 6 GHz. For example, the communication links can serve FrequencyRange 1 (FR1), Frequency Range 2 (FR2), or a combination thereof. In oneembodiment, one or more of the mobile devices support a HPUE power classspecification.

In certain implementations, a base station and/or user equipmentcommunicates using beamforming. For example, beamforming can be used tofocus signal strength to overcome path losses, such as high lossassociated with communicating over high signal frequencies. In certainembodiments, user equipment, such as one or more mobile phones,communicate using beamforming on millimeter wave frequency bands in therange of 30 GHz to 300 GHz and/or upper centimeter wave frequencies inthe range of 6 GHz to 30 GHz, or more particularly, 24 GHz to 30 GHz.

Different users of the communication network 10 can share availablenetwork resources, such as available frequency spectrum, in a widevariety of ways.

In one example, frequency division multiple access (FDMA) is used todivide a frequency band into multiple frequency carriers. Additionally,one or more carriers are allocated to a particular user. Examples ofFDMA include, but are not limited to, single carrier FDMA (SC-FDMA) andorthogonal FDMA (OFDMA). OFDMA is a multicarrier technology thatsubdivides the available bandwidth into multiple mutually orthogonalnarrowband subcarriers, which can be separately assigned to differentusers.

Other examples of shared access include, but are not limited to, timedivision multiple access (TDMA) in which a user is allocated particulartime slots for using a frequency resource, code division multiple access(CDMA) in which a frequency resource is shared amongst different usersby assigning each user a unique code, space-divisional multiple access(SDMA) in which beamforming is used to provide shared access by spatialdivision, and non-orthogonal multiple access (NOMA) in which the powerdomain is used for multiple access. For example, NOMA can be used toserve multiple users at the same frequency, time, and/or code, but withdifferent power levels.

Enhanced mobile broadband (eMBB) refers to technology for growing systemcapacity of LTE networks. For example, eMBB can refer to communicationswith a peak data rate of at least 10 Gbps and a minimum of 100 Mbps foreach user. Ultra-reliable low latency communications (uRLLC) refers totechnology for communication with very low latency, for instance, lessthan 2 milliseconds. uRLLC can be used for mission-criticalcommunications such as for autonomous driving and/or remote surgeryapplications. Massive machine-type communications (mMTC) refers to lowcost and low data rate communications associated with wirelessconnections to everyday objects, such as those associated with Internetof Things (IoT) applications.

The communication network 10 of FIG. 1A can be used to support a widevariety of advanced communication features, including, but not limitedto, eMBB, uRLLC, and/or mMTC.

FIG. 1B is a schematic diagram of one example of a mobile device 2 acommunicating via cellular and WiFi networks. For example, as shown inFIG. 1B, the mobile device 2 a communicates with a base station 1 of acellular network and with a WiFi access point 3 of a WiFi network. FIG.1B also depicts examples of other user equipment (UE) communicating withthe base station 1, for instance, a wireless-connected car 2 b andanother mobile device 2 c. Furthermore, FIG. 1B also depicts examples ofother WiFi-enabled devices communicating with the WiFi access point 3,for instance, a laptop 4.

Although specific examples of cellular UE and WiFi-enabled devices isshown, a wide variety of types of devices can communicate using cellularand/or WiFi networks. Examples of such devices, include, but are notlimited to, mobile phones, tablets, laptops, Internet of Things (IoT)devices, wearable electronics, customer premises equipment (CPE),wireless-connected vehicles, wireless relays, and/or a wide variety ofother communication devices.

In certain implementations, UE, such as the mobile device 2 a of FIG.1B, is implemented to support communications using a number oftechnologies, including, but not limited to, 2G, 3G, 4G (including LTE,LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (for instance, WiFi),WPAN (for instance, Bluetooth and ZigBee), WMAN (for instance, WiMax),and/or GPS. In certain implementations, enhanced license assisted access(eLAA) is used to aggregate one or more licensed frequency carriers (forinstance, licensed 4G LTE and/or 5G NR frequencies), with one or moreunlicensed carriers (for instance, unlicensed WiFi frequencies).

Furthermore, certain UE can communicate not only with base stations andaccess points, but also with other UE. For example, thewireless-connected car 2 b can communicate with a wireless-connectedpedestrian 2 d, a wireless-connected stop light 2 e, and/or anotherwireless-connected car 2 f using vehicle-to-vehicle (V2V) and/orvehicle-to-everything (V2X) communications.

Although various examples of communication technologies have beendescribed, mobile devices can be implemented to support a wide range ofcommunications.

Various communication links have been depicted in FIG. 1B. Thecommunication links can be duplexed in a wide variety of ways,including, for example, using frequency-division duplexing (FDD) and/ortime-division duplexing (TDD). FDD is a type of radio frequencycommunications that uses different frequencies for transmitting andreceiving signals. FDD can provide a number of advantages, such as highdata rates and low latency. In contrast, TDD is a type of radiofrequency communications that uses about the same frequency fortransmitting and receiving signals, and in which transmit and receivecommunications are switched in time. TDD can provide a number ofadvantages, such as efficient use of spectrum and variable allocation ofthroughput between transmit and receive directions.

Different users of the illustrated communication networks can shareavailable network resources, such as available frequency spectrum, in awide variety of ways. In one example, frequency division multiple access(FDMA) is used to divide a frequency band into multiple frequencycarriers. Additionally, one or more carriers are allocated to aparticular user. Examples of FDMA include, but are not limited to,single carrier FDMA (SC-FDMA) and orthogonal FDMA (OFDMA). OFDM is amulticarrier technology that subdivides the available bandwidth intomultiple mutually orthogonal narrowband subcarriers, which can beseparately assigned to different users.

Other examples of shared access include, but are not limited to, timedivision multiple access (TDMA) in which a user is allocated particulartime slots for using a frequency resource, code division multiple access(CDMA) in which a frequency resource is shared amongst different usersby assigning each user a unique code, space-divisional multiple access(SDMA) in which beamforming is used to provide shared access by spatialdivision, and non-orthogonal multiple access (NOMA) in which the powerdomain is used for multiple access. For example, NOMA can be used toserve multiple users at the same frequency, time, and/or code, but withdifferent power levels.

Certain RF communication systems include multiple transceivers forcommunicating using different wireless networks, over multiple frequencybands, and/or using different communication standards. Althoughimplementing an RF communication system in this manner can expandfunctionality, increase bandwidth, and/or enhance flexibility, a numberof coexistence issues can arise between the transceivers operatingwithin the RF communication system.

For example, an RF communication system can include a cellulartransceiver for processing RF signals communicated over a cellularnetwork and a wireless local area network (WLAN) transceiver forprocessing RF signals communicated over a WLAN network, such as a WiFinetwork. For instance, the mobile device 2 a of FIG. 1B is operable tocommunicate using cellular and WiFi networks.

Although implementing the RF communication system in this manner canprovide a number of benefits, a mutual desensitization effect can arisefrom cellular transmissions interfering with reception of WiFi signalsand/or from WiFi transmissions interfering with reception of cellularsignals.

In one example, cellular Band 7 can give rise to mutual desensitizationwith respect to 2.4 Gigahertz (GHz) WiFi. For instance, Band 7 has anFDD duplex and operates over a frequency range of about 2.62 GHz to 2.69GHz for downlink and over a frequency range of about 2.50 GHz to about2.57 GHz for uplink, while 2.4 GHz WiFi has TDD duplex and operates overa frequency range of about 2.40 GHz to about 2.50 GHz. Thus, cellularBand 7 and 2.4 GHz WiFi are adjacent in frequency, and RF signal leakagedue to the high power transmitter of one transceiver/front end affectsreceiver performance of the other transceiver/front end, particularly atborder frequency channels.

In another example, cellular Band 40 and 2.4 GHz WiFi can give rise tomutual desensitization. For example, Band 40 has a TDD duplex andoperates over a frequency range of about 2.30 GHz to about 2.40 GHz,while 2.4 GHz WiFi has TDD duplex and operates over a frequency range ofabout 2.40 GHz to about 2.50 GHz. Accordingly, cellular Band 40 and 2.4GHz WiFi are adjacent in frequency and give rise to a number ofcoexistence issues, particularly at border frequency channels.

Desensitization can arise not only from direct leakage of an aggressortransmit signal to a victim receiver, but also from spectral regrowthcomponents generated in the transmitter. Such interference can lierelatively closely in frequency with the victim receive signal and/ordirectly overlap it.

FIG. 2 is a schematic diagram of one embodiment of a mobile device 800.The mobile device 800 includes a baseband system 801, a transceiver 802,a front end system 803, antennas 804, a power management system 805, amemory 806, a user interface 807, and a battery 808.

The mobile device 800 can be used communicate using a wide variety ofcommunications technologies, including, but not limited to, 2G, 3G, 4G(including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (forinstance, WiFi), WPAN (for instance, Bluetooth and ZigBee), WMAN (forinstance, WiMax), and/or GPS technologies.

The transceiver 802 generates RF signals for transmission and processesincoming RF signals received from the antennas 804. It will beunderstood that various functionalities associated with the transmissionand receiving of RF signals can be achieved by one or more componentsthat are collectively represented in FIG. 2 as the transceiver 802. Inone example, separate components (for instance, separate circuits ordies) can be provided for handling certain types of RF signals.

The front end system 803 aids in conditioning signals transmitted toand/or received from the antennas 804. In the illustrated embodiment,the front end system 803 includes antenna tuning circuitry 810, poweramplifiers (PAs) 811, low noise amplifiers (LNAs) 812, filters 813,switches 814, and signal splitting/combining circuitry 815. However,other implementations are possible.

For example, the front end system 803 can provide a number offunctionalities, including, but not limited to, amplifying signals fortransmission, amplifying received signals, filtering signals, switchingbetween different bands, switching between different power modes,switching between transmission and receiving modes, duplexing ofsignals, multiplexing of signals (for instance, diplexing ortriplexing), or some combination thereof.

In certain implementations, the mobile device 800 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 804 can include antennas used for a wide variety of typesof communications. For example, the antennas 804 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 804 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The mobile device 800 can operate with beamforming in certainimplementations. For example, the front end system 803 can includeamplifiers having controllable gain and phase shifters havingcontrollable phase to provide beam formation and directivity fortransmission and/or reception of signals using the antennas 804. Forexample, in the context of signal transmission, the amplitude and phasesof the transmit signals provided to the antennas 804 are controlled suchthat radiated signals from the antennas 804 combine using constructiveand destructive interference to generate an aggregate transmit signalexhibiting beam-like qualities with more signal strength propagating ina given direction. In the context of signal reception, the amplitude andphases are controlled such that more signal energy is received when thesignal is arriving to the antennas 804 from a particular direction. Incertain implementations, the antennas 804 include one or more arrays ofantenna elements to enhance beamforming.

The baseband system 801 is coupled to the user interface 807 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 801 provides the transceiver 802with digital representations of transmit signals, which the transceiver802 processes to generate RF signals for transmission. The basebandsystem 801 also processes digital representations of received signalsprovided by the transceiver 802. As shown in FIG. 2, the baseband system801 is coupled to the memory 806 of facilitate operation of the mobiledevice 800.

The memory 806 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of themobile device 800 and/or to provide storage of user information.

The power management system 805 provides a number of power managementfunctions of the mobile device 800. In certain implementations, thepower management system 805 includes a PA supply control circuit thatcontrols the supply voltages of the power amplifiers 811. For example,the power management system 805 can be configured to change the supplyvoltage(s) provided to one or more of the power amplifiers 811 toimprove efficiency, such as power added efficiency (PAE).

As shown in FIG. 2, the power management system 805 receives a batteryvoltage from the battery 808. The battery 808 can be any suitablebattery for use in the mobile device 800, including, for example, alithium-ion battery.

FIG. 3 is a schematic diagram of a power amplifier system 860 accordingto one embodiment. The illustrated power amplifier system 860 includes abaseband processor 841, a transmitter/observation receiver 842, a poweramplifier (PA) 843, a directional coupler 844, front-end circuitry 845,an antenna 846, a PA bias control circuit 847, and a PA supply controlcircuit 848. The illustrated transmitter/observation receiver 842includes an I/Q modulator 857, a mixer 858, and an analog-to-digitalconverter (ADC) 859. In certain implementations, thetransmitter/observation receiver 842 is incorporated into a transceiver.

The baseband processor 841 can be used to generate an in-phase (I)signal and a quadrature-phase (Q) signal, which can be used to representa sinusoidal wave or signal of a desired amplitude, frequency, andphase. For example, the I signal can be used to represent an in-phasecomponent of the sinusoidal wave and the Q signal can be used torepresent a quadrature-phase component of the sinusoidal wave, which canbe an equivalent representation of the sinusoidal wave. In certainimplementations, the I and Q signals can be provided to the I/Qmodulator 857 in a digital format. The baseband processor 841 can be anysuitable processor configured to process a baseband signal. Forinstance, the baseband processor 841 can include a digital signalprocessor, a microprocessor, a programmable core, or any combinationthereof. Moreover, in some implementations, two or more basebandprocessors 841 can be included in the power amplifier system 860.

The I/Q modulator 857 can be configured to receive the I and Q signalsfrom the baseband processor 841 and to process the I and Q signals togenerate an RF signal. For example, the I/Q modulator 857 can includedigital-to-analog converters (DACs) configured to convert the I and Qsignals into an analog format, mixers for upconverting the I and Qsignals to RF, and a signal combiner for combining the upconverted I andQ signals into an RF signal suitable for amplification by the poweramplifier 843. In certain implementations, the I/Q modulator 857 caninclude one or more filters configured to filter frequency content ofsignals processed therein.

The power amplifier 843 can receive the RF signal from the I/Q modulator857, and when enabled can provide an amplified RF signal to the antenna846 via the front-end circuitry 845.

The front-end circuitry 845 can be implemented in a wide variety ofways. In one example, the front-end circuitry 845 includes one or moreswitches, filters, diplexers, multiplexers, and/or other components. Inanother example, the front-end circuitry 845 is omitted in favor of thepower amplifier 843 providing the amplified RF signal directly to theantenna 846.

The directional coupler 844 senses an output signal of the poweramplifier 823. Additionally, the sensed output signal from thedirectional coupler 844 is provided to the mixer 858, which multipliesthe sensed output signal by a reference signal of a controlledfrequency. The mixer 858 operates to generate a downshifted signal bydownshifting the sensed output signal's frequency content. Thedownshifted signal can be provided to the ADC 859, which can convert thedownshifted signal to a digital format suitable for processing by thebaseband processor 841. Including a feedback path from the output of thepower amplifier 843 to the baseband processor 841 can provide a numberof advantages. For example, implementing the baseband processor 841 inthis manner can aid in providing power control, compensating fortransmitter impairments, and/or in performing digital pre-distortion(DPD). Although one example of a sensing path for a power amplifier isshown, other implementations are possible.

The PA supply control circuit 848 receives a power control signal fromthe baseband processor 841, and controls supply voltages of the poweramplifier 843. In the illustrated configuration, the PA supply controlcircuit 848 generates a first supply voltage V_(CC1) for powering aninput stage of the power amplifier 843 and a second supply voltageV_(CC2) for powering an output stage of the power amplifier 843. The PAsupply control circuit 848 can control the voltage level of the firstsupply voltage V_(CC1) and/or the second supply voltage V_(CC2) toenhance the power amplifier system's PAE.

The PA supply control circuit 848 can employ various power managementtechniques to change the voltage level of one or more of the supplyvoltages over time to improve the power amplifier's power addedefficiency (PAE), thereby reducing power dissipation.

One technique for improving efficiency of a power amplifier is averagepower tracking (APT), in which a DC-to-DC converter is used to generatea supply voltage for a power amplifier based on the power amplifier'saverage output power. Another technique for improving efficiency of apower amplifier is envelope tracking (ET), in which a supply voltage ofthe power amplifier is controlled in relation to the envelope of the RFsignal. Thus, when a voltage level of the envelope of the RF signalincreases the voltage level of the power amplifier's supply voltage canbe increased. Likewise, when the voltage level of the envelope of the RFsignal decreases the voltage level of the power amplifier's supplyvoltage can be decreased to reduce power consumption.

In certain configurations, the PA supply control circuit 848 is amulti-mode supply control circuit that can operate in multiple supplycontrol modes including an APT mode and an ET mode. For example, thepower control signal from the baseband processor 841 can instruct the PAsupply control circuit 848 to operate in a particular supply controlmode.

As shown in FIG. 3, the PA bias control circuit 847 receives a biascontrol signal from the baseband processor 841, and generates biascontrol signals for the power amplifier 843. In the illustratedconfiguration, the bias control circuit 847 generates bias controlsignals for both an input stage of the power amplifier 843 and an outputstage of the power amplifier 843. However, other implementations arepossible.

FIG. 4A is a schematic diagram of one embodiment of a packaged module900. FIG. 4B is a schematic diagram of a cross-section of the packagedmodule 900 of FIG. 4A taken along the lines 4B-4B.

The packaged module 900 includes radio frequency components 901, asemiconductor die 902, surface mount devices 903, wirebonds 908, apackage substrate 920, and an encapsulation structure 940. The packagesubstrate 920 includes pads 906 formed from conductors disposed therein.Additionally, the semiconductor die 902 includes pins or pads 904, andthe wirebonds 908 have been used to connect the pads 904 of the die 902to the pads 906 of the package substrate 920.

The semiconductor die 902 includes a power amplifier 945, which can beimplemented in accordance with one or more features disclosed herein.

The packaging substrate 920 can be configured to receive a plurality ofcomponents such as radio frequency components 901, the semiconductor die902 and the surface mount devices 903, which can include, for example,surface mount capacitors and/or inductors. In one implementation, theradio frequency components 901 include integrated passive devices(IPDs).

As shown in FIG. 4B, the packaged module 900 is shown to include aplurality of contact pads 932 disposed on the side of the packagedmodule 900 opposite the side used to mount the semiconductor die 902.Configuring the packaged module 900 in this manner can aid in connectingthe packaged module 900 to a circuit board, such as a phone board of amobile device. The example contact pads 932 can be configured to provideradio frequency signals, bias signals, and/or power (for example, apower supply voltage and ground) to the semiconductor die 902 and/orother components. As shown in FIG. 4B, the electrical connectionsbetween the contact pads 932 and the semiconductor die 902 can befacilitated by connections 933 through the package substrate 920. Theconnections 933 can represent electrical paths formed through thepackage substrate 920, such as connections associated with vias andconductors of a multilayer laminated package substrate.

In some embodiments, the packaged module 900 can also include one ormore packaging structures to, for example, provide protection and/orfacilitate handling. Such a packaging structure can include overmold orencapsulation structure 940 formed over the packaging substrate 920 andthe components and die(s) disposed thereon.

It will be understood that although the packaged module 900 is describedin the context of electrical connections based on wirebonds, one or morefeatures of the present disclosure can also be implemented in otherpackaging configurations, including, for example, flip-chipconfigurations.

FIG. 5 is a schematic diagram of one embodiment of an RF communicationsystem 1620 including a transceiver/RF front end 1603 (or simply RFfront end). In detail, the RF communication system includes a basebandmodem 1602, the RF front end 1603, power management 1604, and aplurality of antennas 1601 a-1601 n.

The RF front end 1603 is connected to the baseband modem 1602 to receiveand transmit baseband signals to/from the baseband modem 1602. Thebaseband signals received from the baseband modem 1602 processed by theRF front end to be wirelessly transmitted via the antennas 1601 a-1601n. Similarly, RF signals received via the antennas 1601 a-1601 n areprocessed by the RF front end 1603 and before being provided to thebaseband modem 1602.

The power management 1604 provides power to each of the baseband modem1602 and the RF front end 1603. To this end, the power management 1604includes a power management unit (PMU) baseband 1611 configured toprovide power to the baseband modem 1602 and a PMU RF 1612 configured toprovide power to the RF front end 1603.

The RF front end 1603 includes a MUX/DEMUX block 1605, a beamformingblock 1606, a data conversion block 1607, a mixing block 1608, anamplification block 1609, and a filtering/switching block 1610. TheMUX/DEMUX block 1605 can be configured to control the flow of RF signalsto/from the baseband modem 1602 through a plurality of communicationband paths through the remainder of the RF front end 1603. Thebeamforming block 1606 is configured to adjust the gain and/or phase ofthe plurality of RF signals to direct beams to focus signal strength ina desired direction for RF signals transmitted and received from theantennas 1601 a-1601 n.

The data conversion block 1607 can contain a plurality of DACsconfigured to convert the signals received from the beamforming block1606 into an analog format. The data conversion block 1607 can alsocontain a plurality of ADCs configured to convert analog signalsreceived from the mixing block 1608 into a digital format. The mixingblock 1608 can include a plurality of local oscillators (LOs) and isconfigured to upconvert the analog signals received from the dataconversion block 1607 and downconvert the signals received from theamplification block 1609.

The amplification block 1609 can include a plurality of PAs configuredto amplify signals received from the mixing block and a plurality ofLNAs configured to amplify signals received from the filtering/switchingblock 1610. The filtering/switching block 1610 includes a plurality offilters configured to filter out frequencies that do not form a part ofa correspond communication band and a plurality of switches configuredto selectively connect the antennas 1601 a-1601 n to one or more of thecommunication bands.

Embodiments of RF Front End Modules

As described above, communications systems typically include an RF frontend designed to connect a baseband model to one or more antennas andprocess the RF signals communicated therebetween.

In traditional TDD RF front ends (RFFE) for cell phones, a common filtercan be used for both the transmit and receive paths to save area andcost. There may be conflicting design goals for such common filters,which include (a) a sufficiently high rejection in the receive mode forblockers relatively close to the band edge such as 3GPP range 3blockers, and (b) a sufficiently low insertion loss in the transmit modeto have a module with high efficiency. For certain bands, it can be moredifficult to achieve the above described design goals when a given bandis spaced relatively close to another band. For example, within the 5Gstandard, band n79 is located only 125 MHz away from the high edge ofthe band for the first WiFi 5 GHz channel. As another example, for the5G band n77, strong HB and WiFi 2.4 GHz blockers are located only a fewhundred MHz away from the lower edge of the n77 band.

In addition, there are stringent regulatory requirement for 5G NR, whichinclude a requirement that power amplifiers exhibit high linearity(e.g., a threshold level of linearity) to prevent unwanted emissions inadjacent public bands and military bands. To save area for compact cellphones, the n77 and n79 bands may be routed through a multiplexer to acommon antenna. The n77 and n79 bands are two examples of 5G NR TDDbands where TX and RX share a common path to the antenna port of an RFFEmodule. Similarly, a multiplexer can be used such that the n79 band pathis shared between n79 transmit and n79 receive.

Another challenging trade-off exists for band B41 when coexistence withWiFi imposes more than 50 dB rejection of transmit noise on the lowerside of the B41 band without impacting the filter insertion loss duringthe receive period of a TDD frame.

FIG. 6A is an example multiband RF front end 203 which can be used forTDD in accordance with aspects of this disclosure. The example RF frontend 203 may be configured to transmit/receive N bands Band 1, Band 2, .. . , Band N. The RF front end 203 includes a plurality of poweramplifiers 204A, 204B, . . . , 204N; a plurality of low noise amplifiers206A, 206B, . . . , 206N; a plurality of transmit/receive switches 208A,208B, . . . , 208N; and a multiplexer 210 including a plurality offilters 210A, 210B, . . . , 210N.

With reference to Band 1 as an example, each band within the RF frontend 203 may have a dedicated power amplifier 204A for a transmit pathand a dedicated low noise amplifier 206A in a receive path. The transmitand receive paths for Band 1 are combined via the correspondingtransmit/receive switch 208A. Each of the transmit/receive switches208A-208N are connected to the multiplexer 210 to connect the bands Band1-Band N to the output node to be connected to one or more antennas. Thefilters 210A-210N may be implemented as band-pass filters configured topass frequencies associated with the corresponding bands Band 1-Band N.

FIG. 6B is another example multiband RF front end 203 which can be usedfor TDD in accordance with aspects of this disclosure. In particular,the RF front end 203 of FIG. 6B may be configured as a high performanceTDD RF front end 203. Similar to the example of FIG. 6A, the example RFfront end 203 may be configured to transmit/receive N bands Band 1, Band2, . . . , Band N. The RF front end 203 includes a plurality of poweramplifiers 204A, 204B, . . . , 204N; a plurality of low noise amplifiers206A, 206B, . . . , 206N; a first filter bank 210 including a firstplurality of filters 210A, 210B, . . . , 210N; a second filter bank 212including a second plurality of filters 212A, 212B, . . . , 212N; and asingle-pole N-throw transmit/receive switch 214.

In order to provide improved performance compared to FIG. 6A, there aretwo sets of individual filters in the embodiment of FIG. 6B, the firstfilters 210A-210N for transmit RF signals and the second filters212A-212N for receive RF signals. In implementation in which the RFfront end 203 supports simultaneously transmitting and receiving betweenconstituent bands Band 1-Band N, the transmit and receive paths areconnected to the transmit/receive switch 214 which can be configured toconnect multiple receive paths and transmit paths concurrently to theoutput node to be connected to one or more antennas.

FIG. 6C is yet another example multiband RF front end 203 which can beused for TDD in accordance with aspects of this disclosure. Inparticular, the RF front end 203 of FIG. 6B may be configured as anotherexample of a high performance TDD RF front end 203. Compared to FIG. 6B,the embodiment of FIG. 6C has lower insertion loss (thus higher TXefficiency) because the TDD switch has a fewer number of throws. Similarto the example of FIG. 6B, the example RF front end 203 may beconfigured to transmit/receive N bands Band 1, Band 2, . . . , Band N.The RF front end 203 includes a plurality of power amplifiers 204A,204B, . . . , 204N; a plurality of low noise amplifiers 206A, 206B, . .. , 206N; a first multiplexer 210 including a first plurality of filters210A, 210B, . . . , 210N; a second multiplexer 212 including a secondplurality of filters 212A, 212B, . . . , 212N; and a single-poledouble-throw transmit/receive switch 216.

In implementation in which the RF front end 203 does not supportsimultaneous receive and transmit between constituent bands Band 1-BandN, the transmit/receive switch 216 is connected to a common node of eachof the first and second multiplexers 210 and 212 to be selectivelyconnected to the output node.

FIG. 7A illustrates an example portion of an RF front end 310 for twobands in accordance with aspects of this disclosure. As shown in FIG.7A, the RF front end 310 includes a first power amplifier 402, a secondpower amplifier 404, a first low noise amplifier 406, a second low noiseamplifier 408, a first transmit/receive switch 410, a secondtransmit/receive switch 412, and a diplexer 414.

The first power amplifier 402, the first low noise amplifier 406, andthe first switch 410 may be configured to transmit and receive RFsignals for a first band using TDD while the second power amplifier 404,the second low noise amplifier 408, and the second switch 412 may beconfigured to transmit and receive RF signals for a second band usingTDD. The first and second transmit/receive switches 410 and 412 can beconfigured such that each of the first and second bands is in either atransmit or a receive mode. The diplexer 414 may be formed of a pair ofband-pass filters, which respectively pass RF signals corresponding tothe first and second bands between the output node and the respectivefirst and second transmit/receive switches 410 and 412.

For certain bands (e.g., bands n77 and n79), aspects of this disclosurerelate to addressing at least some of the above-described challengesrelated to closely spaced band. For example, aspects of this disclosurerelate to addressing the conflicting design goals of (a) a sufficientlyhigh rejection in the receive mode for blockers relatively close to theband edge such as 3GPP range 3 blockers, and (b) a sufficiently lowinsertion loss in the transmit mode to have a module with highefficiency. Since in the embodiment of FIG. 7A, a common filter is usedfor both RX and TX, the conflicting design goals may result incompromise in either rejection or insertion loss.

FIG. 7B illustrates another example portion of an RF front end 310 fortwo bands in accordance with aspects of this disclosure. In thisimplementation, the RF front end 310 includes a first power amplifier402, a second power amplifier 404, a first low noise amplifier 406, asecond low noise amplifier 408, a first transmit/receive switch 410, asecond transmit/receive switch 412, a first diplexer 416, and a seconddiplexer 418.

In the FIG. 7B example, rather than using a common diplexer (e.g., suchas the diplexer 414 of FIG. 7A) for both receive and transmit modes ofTDD, the FIG. 7B embodiment includes separate first and second diplexers416 and 418, which can be configured to address different set ofspecifications and/or design constraints for the receive and transmitpaths.

For example, the second diplexer 418 on the receive side is configuredto filter signals received from the output node before providing thefiltered signals to the low noise amplifiers 406 and 408. The secondfilter 418 can be configured to reject RF signals at close-infrequencies (from the band edge) in order to reject blockers that canproduce unwanted in-band intermodulation distortion (IMD) components.Due to the additional rejection properties of the receive filtersforming the diplexer 218, the insertion loss of the diplexer may becomparatively higher than a diplexer without these rejections.

The first diplexer 416 on the transmit side may have relativelypermissive rejection specifications and/or design constraints comparedto receive path. Thus, the first diplexer 416 on the transmit side canbe configured with significantly lower insertion loss compared to seconddiplexer 418 on the receive side, thereby improving system efficiencyfor the RF front end 310.

Additionally, the FIG. 7B embodiment employs a different placement ofthe first and second transmit/receive switches 410 and 412 compared tothe embodiment of FIG. 7A. That is, in the implementation of FIG. 7B thefirst and second transmit/receive switches 410 and 412 are locatedbetween the first and second diplexers 416 and 418 and the output node,whereas in the implementation of FIG. 7A, the first and secondtransmit/receive switches 410 and 412 are located between the diplexer414 and each of the first and second power amplifiers 402 and 404 andfirst and second low noise amplifiers 406 and 408.

The configuration of FIG. 7B may be used in a 5G Ultra High-Band (UHB)RF front end 310. For example, the first and second diplexers 416 and418 can be separated for the transmit and receive paths instead of usinga single diplexer for both the transmit and receive paths as shown inFIG. 7A.

FIG. 7C illustrates yet another example portion of an RF front end 310for two bands in accordance with aspects of this disclosure. In thisimplementation, the RF front end 310 includes a first power amplifier402, a second power amplifier 404, a first low noise amplifier 406, asecond low noise amplifier 408, a first diplexer 416, a second diplexer418, and a single-pole quadruple-throw (SP4T) switch 420.

The FIG. 7C implementation may be used in situations when concurrentoperation of the first and second bands is not required. For example,the SP4T switch 420 can be used in place of the first and secondtransmit/receive switches 410 and 412 when concurrent operation of thefirst and second bands is not required. The use of a SP4T switch 420 asshown in FIG. 7C can reduce the insertion loss compared to the FIG. 7Bembodiment, and thus, improve the performance for both the receive andtransmit modes.

FIG. 7D illustrates still yet another example portion of an RF front end310 for two bands in accordance with aspects of this disclosure. In thisimplementation, the RF front end 310 includes a first power amplifier402, a second power amplifier 404, a first low noise amplifier 406, asecond low noise amplifier 408, a first diplexer 416, a second diplexer418, and a double-pole quadruple-throw (2P4T) switch 422.

The FIG. 7D implementation may be used enable asynchronous operationbetween the first and second bands, for example, by replacing the SP4Tswitch 420 with the 2P4T switch 422. In this embodiment, band 1 (e.g.,n77) could be in TX mode while simultaneously band 2 (e.g., n79) couldin the RX mode. Such asynchronous operation is prevalent is many currentand future 5G networks.

FIG. 8 illustrates an example portion of an RF front end 310 for threebands in accordance with aspects of this disclosure. In certainimplementations, the RF front end 310 may be configured fortransmitting/receiving RF signals for two mid-bands (e.g., band B34 andband B39) and a single high-band (e.g., band n41).

The RF front end 310 of FIG. 8 includes a mid-band power amplifier 502,a high-band power amplifier 504, a mid-band low noise amplifier 506, ahigh-band low noise amplifier 508, a first SPDT switch 510, a secondSPDT switch 512, a first triplexer 514, a second triplexer 516, and a2P6T switch 518.

For certain combinations of bands, the high-band may not be synchronouswith certain mid-bands. For example, the operation of band n41 may notbe synchronized with mid-band anchors B34 and B39. However, overlapbetween receive and transmit period of TDD frames may be possible, andthus, the 2P6T switch 518 includes two poles to allow for this overlap.

To enable asynchronous operation between the mid-bands and thehigh-band, the first triplexer 514 on the transmit path and the secondtriplexer 516 on the receive side can be separated. However, the 2P6Tswitch includes two poles to enable simultaneous receive and transmitoperations.

FIG. 9A illustrates an example portion of an RF front end 310 for asingle band in accordance with aspects of this disclosure. As shown inFIG. 9A, the RF front end 310 includes a power amplifier 602, a lownoise amplifier 604, a transmit/receive switch 606, and a pass-bandfilter 608.

FIG. 9B illustrates another example portion of an RF front end 310 for asingle band in which separate filters are provided for the transmit andreceive paths in accordance with aspects of this disclosure. As shown inFIG. 9B, the RF front end 310 includes a power amplifier 602, a lownoise amplifier 604, a transmit filter 610, a receive filter 612, and aswitch 614. In comparison to FIG. 9A, rather than using a single filter608 for both of the transmit and receive paths, the FIG. 9Bimplementation separates the filters into the transmit filter 610 andthe receive filter 612. This separation of the transmit and receivefilters 610 and 612 enables the same improvements (e.g., enhanced blockon the receive path and low insertion loss on the transmit path) asthose discussed above in connection with FIG. 7B.

In certain embodiments, each band (e.g., all TDD LTE/NR bands) for agiven RF communication system can be implemented using the layoutdescribed in connection with FIG. 9B.

However, it may also be possible to reduce the size and cost of theimplementation by combining at least part of the receive and transmitfilters for certain bands. FIG. 9C illustrates an example portion of anRF front end 310 for a single band in accordance with aspects of thisdisclosure. As shown in FIG. 9A, the RF front end 310 includes a poweramplifier 602, a low noise amplifier 604, a transmit filter 610, areceive filter 612, a switch 614, and a common filter 616. By includingthe common filter 616 on the shared path between the switch 614 and theoutput node, the components of the common filter 616 do not need to beduplicated in each of the transmit filter 610 and the receive filter612, and thus, the overall size of the RF front end 310 can be reducedcompared to the FIG. 9B implementation. Further, by having the separatetransmit and receive filters 610 and 612, the benefits associated withseparate filters can also be achieved in this embodiment.

FIG. 10A illustrates an example portion of an RF front end 310 for asingle band in accordance with aspects of this disclosure. The RF frontend 310 illustrated in FIG. 10A includes a power amplifier 702, a lownoise amplifier 704, a transmit filter 706, a receive filter 708, afirst switch 710, a second switch 712, a first supplemental filter 714,a second supplemental filter 716, and a common filter 718.

The common filter 718 performs a similar function to the common filter616 of FIG. 9C on the shared path between the first switch 712 and theoutput node. That is, the components of the common filter 718 do notneed to be duplicated in each of the transmit filter 796 and the receivefilter 708, and thus, the overall size of the RF front end 310 can bereduced compared to the FIG. 9B implementation.

In the embodiments of FIGS. 9B and 9C, the switch 614 enables the RFfront ends 310 to select a dynamic change in signal path filtering(e.g., a selection of either the transmit filter 610 on the transmitpath or the receive filter 612 on the receive path). In contrast, inFIG. 10A, the first and second switches 710 and 712 are ganged togetherin order to dynamically reconfigure the transmit and receive filters inmore complex manners by switching in one of the first and secondsupplemental filters 714 and 716 into the signal path. In the FIG. 10Aembodiment, the first and second supplementary filters 714 and 176 maybe implemented as shunt filters to ground in order to reject certainportions of the RF spectrum. The first and second supplementary filters714 and 716 are switched in to form part of the transmit and receivepaths and may be entirely different from the transmit and receivefilters 706 and 708 not only in center frequency but also in frequencyresponse.

FIG. 10B illustrates another example portion of an RF front end 310 fora single band in accordance with aspects of this disclosure. The RFfront end 310 illustrated in FIG. 10B includes a power amplifier 702, alow noise amplifier 704, a transmit filter 706, a receive filter 708, afirst switch 710, a second switch 712, a first supplemental filter 714,a second supplemental filter 716, and a common filter 718.

In the FIG. 10B embodiment, the first and second supplemental filters714 and 716 are switched in to form part of the transmit and receivepaths and may be implemented as shunt notch filters.

When the FIG. 10B RF front end 310 is implemented for band B41, thefirst supplemental filter 714 may be switched into the transmit path forthe transmit period and may have a notch at the frequency of WiFi 2.4GHz communication frequency ensures that B41 emission into the WiFi isreduced below a threshold level to ensure that the B41 band transmitterdoes not interfere with coexisting WiFi radio. Continuing with the bandB41 implementation, the second supplemental filter 716 may be switchedinto the receive path during the receive period and may have a notch ata frequency of the B39 band to ensure that the B39 transmitter isattenuated sufficiently to prevent saturation or IMD generation in theB41 low noise amplifier 704.

Conclusion

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Likewise, the word “connected”, as generally used herein, refers to twoor more elements that may be either directly connected, or connected byway of one or more intermediate elements. Additionally, the words“herein,” “above,” “below,” and words of similar import, when used inthis application, shall refer to this application as a whole and not toany particular portions of this application. Where the context permits,words in the above Detailed Description using the singular or pluralnumber may also include the plural or singular number respectively. Theword “or” in reference to a list of two or more items, that word coversall of the following interpretations of the word: any of the items inthe list, all of the items in the list, and any combination of the itemsin the list.

Moreover, conditional language used herein, such as, among others,“can,” “could,” “might,” “can,” “e.g.,” “for example,” “such as” and thelike, unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or states. Thus, such conditional language is notgenerally intended to imply that features, elements and/or states are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/orstates are included or are to be performed in any particular embodiment.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A radio frequency front end system comprising: atleast one power amplifier configured to amplify a transmit radiofrequency signal and at least one low noise amplifier configured toreceive a receive radio frequency signal; a first switch configured toselectively couple an output node coupled to an antenna to the at leastone power amplifier during a transmit period and to the at least one lownoise amplifier during a receive period; at least one transmit filtercoupled between the power amplifier and the at least one switch and atleast one receive filter coupled between the low noise amplifier and theat least one switch, a transmit supplemental filter and a receivesupplemental filter; and a second switch configured to selectivelycouple the transmit supplemental filter to the at least one poweramplifier during the transmit period and to couple the receivesupplemental filter to the at least one low noise amplifier during thereceive period.
 2. The front end system of claim 1 wherein the firstswitch and the second switch are ganged together.
 3. The front endsystem of claim 1 further comprising a common filter coupled between thefirst switch and the output node.
 4. The front end system of claim 1wherein the at least one power amplifier includes a plurality of poweramplifiers, and the at least one low noise amplifier includes aplurality of low noise amplifiers.
 5. The front end system of claim 1wherein the transmit and receive supplemental filters include shuntfilters.
 6. The front end system of claim 5 wherein the shunt filtersare configured to reject predetermined portions of an RF spectrum. 7.The front end system of claim 1 wherein the transmit and receivesupplemental filters include notch filters.
 8. The front end system ofclaim 1 wherein the transmit and receive supplemental filters areentirely different from the at least one transmit filter and the atleast one receive filter in center frequency and frequency response. 9.The front end system of claim 1 wherein the second switch is furtherconfigured to dynamically reconfigure the least one transmit filter andthe at least one receive filter by switching in one of the first andsecond supplemental filters into a signal path between at least onepower amplifier, the at least one low noise amplifier; and the outputnode.
 10. A mobile device comprising: an antenna configured to transmitradio frequency signals to a base station; and a front end systemcoupled to the antenna and configured to transmit and receive the radiofrequency signals from the antenna, the front end system including a atleast one power amplifier configured to amplify a transmit radiofrequency signal, at least one low noise amplifier configured to receivea receive radio frequency signal, a first switch configured toselectively couple the antenna to the at least one power amplifierduring a transmit period and to the at least one low noise amplifierduring a receive period, at least one transmit filter coupled betweenthe power amplifier and the at least one switch, at least one receivefilter coupled between the low noise amplifier and the at least oneswitch, a transmit supplemental filter, a receive supplemental filter,and a second switch configured to selectively couple the transmitsupplemental filter to the at least one power amplifier during thetransmit period and to couple the receive supplemental filter to the atleast one low noise amplifier during the receive period.
 11. The mobiledevice of claim 10 wherein the first switch and the second switch areganged together.
 12. The mobile device of claim 10 wherein the front endsystem further includes a common filter coupled between the first switchand the output node.
 13. The mobile device of claim 10 wherein the atleast one power amplifier includes a plurality of power amplifiers, andthe at least one low noise amplifier includes a plurality of low noiseamplifiers.
 14. The mobile device of claim 10 wherein the transmit andreceive supplemental filters include shunt filters.
 15. The mobiledevice of claim 14 wherein the shunt filters are configured to rejectpredetermined portions of an RF spectrum.
 16. The mobile device of claim10 wherein the transmit and receive supplemental filters include notchfilters.
 17. The mobile device of claim 10 wherein the transmit andreceive supplemental filters are entirely different from the at leastone transmit filter and the at least one receive filter in centerfrequency and frequency response.
 18. A method of operating a radiofrequency front end system, the method comprising: coupling, via a firstswitch, at least one power amplifier to an antenna during a transmitperiod, the first switch coupled to the at least one power amplifier viaat least one transmit filter; coupling, via the first switch, at leastone low noise amplifier to the antenna during a receive period, thefirst switch coupled to the at least one low noise amplifier via atleast one receive filter; coupling, via a second switch, a transmitsupplemental filter to the at least one power amplifier during thetransmit period; and coupling, via the second switch, a receivesupplemental filter to the at least one low noise amplifier during thereceive period.
 19. The method of claim 18 wherein a common filter iscoupled between the at first switch and the antenna.
 20. The method ofclaim 18 wherein the at least one power amplifier includes a pluralityof power amplifiers, and the at least one low noise amplifier includes aplurality of low noise amplifiers.